1. Field of the Invention
The present invention relates to a trigger operated dispensing device, e.g. a trigger sprayer, for mounting on a storage container. The trigger sprayer includes a body, and a pumping mechanism comprising a trigger movably mounted to the body, a piston coupled to the trigger and a cylinder in the body for receiving the piston for pumping fluid and defining a pumping chamber.
The pumping mechanism operates in two working strokes: a fluid intake stroke and a fluid ejection stroke. The fluid intake stroke sucks liquid out of the container into the pumping chamber. The fluid ejection stroke discharges the fluid from the pumping chamber through a nozzle assembly of the trigger sprayer into the atmosphere. The fluid ejection stroke is carried out by the operator squeezing the trigger and the fluid intake stroke is carried out by a biasing mechanism, such as a spring or spring assembly, of the pumping mechanism.
More specifically, the present invention relates to a biasing mechanism comprising a plastic spring assembly, which is mounted outside of the pumping chamber between the trigger and the body and which acts on the trigger.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97-1.99
It is well known in the art of trigger sprayers to mount a metal spring in a pumping chamber of a pumping mechanism in a trigger sprayer. The spring acts against a piston coupled to the trigger for urging the trigger to it's home, at rest, position when the trigger is released.
Heretofore, it has also been proposed to provide plastic springs or flexures in trigger sprayers. Some examples of these previously proposed trigger sprayers are disclosed in the following patents:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 4,915,263 Corba 4,273,290 Quinn 4,241,853 Pauls et al. ______________________________________
In the Corba U.S. Pat. No. 4,915,263 a trigger sprayer having a plastic frame, including a trigger, an upper leg and a lower leg with a flexure therebetween and a cap, together with a pumping device, a nozzle assembly and a delivery arm is disclosed. The pumping device is mounted in the cap of the frame and a tubular extension of the pumping device is inserted through an opening of the cap to be press-fitted to the delivery arm to create a connection between the container and the nozzle assembly, mounted at the delivery arm.
The pumping device of the sprayer is mainly made out of plastic, but includes a coiled spring made out of metal to provide a return force to the frame and the trigger handle. The frame, the nozzle and the delivery arm of the trigger sprayer are molded out of plastic material. As a part of the frame of the trigger sprayer, the flexure is located between the upper and lower leg of the frame and is also made out of plastic and urges the trigger handle to its home position.
The frame, including the trigger handle, the upper and lower leg, the flexure, and the cap is molded as one piece of plastic. The flexure enables the trigger handle to be moved inwardly and downwardly. After the trigger handle is released, the plastic material of the frame, especially the flexure, is stressed and because of its plastic memory, it urges the frame, including the trigger handle, back to its home position. The returning force of the flexure is minimal and therefore Corba suggests replacing the plastic flexure by a metal flexure, if necessary.
The major returning force of this trigger sprayer is provided by the metal spring of the pumping mechanism, and the main feature of the flexure is to enable arcuate movement of the trigger handle.
The Quinn U.S. Pat. No. 4,273,290 discloses a chamber, next to a nozzle, including a plastic spring, a spin element and a poppet valve therein. The spin element, the poppet valve and the plastic spring are molded as one piece. The spring is formed as a double curved leaf spring and is forced into the chamber so that the spring is permanently compressed and therefore pushes one end of the spin element against the nozzle and the other end urges the poppet valve against an annular shoulder.
The Pauls et al. U.S. Pat. No. 4,241,853 discloses a trigger sprayer, including a one-piece molded shroud secured over the body and having a trigger return spring integrally molded therewith. This spring comprises a pair of depending, resiliently yieldable spring arms disposed in contacting alignment with spaced apart legs of the trigger. Pauls et al. does not disclose the kind of material used for the spring means and it is only speculation from the shading in the Pauls et al. patent drawings that a non-metal material is used.
The plastic spring assembly disclosed herein is significantly different from the prior Corba, Quinn and Pauls et al. biasing mechanism, such as springs and flexures.
As will be described in greater detail hereinafter, the spring assembly of the present invention is positioned between a trigger and the body of the trigger sprayer and is operable, after the operator has carried out an ejection stroke and released the trigger, to urge the trigger back to is home position. Making the spring assembly out of plastic enables the trigger sprayer to be recycled since it takes the place of a conventional metal spring in a cylinder of the pumping chamber.